Prior-art processes have certain advantages, but on the other hand it is also true that they include a number of disadvantages. The feeding of a grape harvest into fermentation vats presents certain problems which are difficult to solve. The fermentation itself requires precaution, above all there being the risk that it will result in the introduction of acid or, in any event in a volatile acidity which is relatively high.
The introduction of acid is the result of secondary fermentation in the presence of glucose, the natural sugar of the grape, which takes place after alcoholic fermentation in the lower layers of the vat where the weight of the contents crushes the grape berries, thereby immediately starting the alcoholic fermentation and making it difficult for the upper layers to achieve intracellular fermentation, i.e. anaerobic metabolism. Stated otherwise, fermentation is not uniform throughout the height of the vat, so that in order to avoid producing an under-fermented product, it becomes necessary to run the risk of the aforementioned acid introduction.
It should also be noted that the particular flavor from aromatic vines is not always present in the resulting wines obtained by prior-art processes of carbonated maceration.